1. Field of the Invention
The present invention relates to a method for increasing the compressor-related pressure drop in the gas turbine of a power plant in accordance with the preamble of claim 1. It also relates to power plants for the application of this method.
2. Discussion of Background
In power plants, the most important aim is, in the final analysis, the maximization of the efficiency of such a plant in order to minimize the exhaust-gas emissions. In this context, attention is drawn to the new generation of gas turbine groups, which are capable of providing efficiencies which were thought to be impossible just a few years ago. So-called combination units form a fairly mature technology. This term refers to the operational interaction of a gas turbine group with at least one steam-turbine circuit connected downstream, the exhaust gases from the gas turbine, which in themselves still have a large energy potential, being passed into a waste-heat steam generator, in which the steam required for acting on the steam turbine is generated. Such a waste-heat steam generator can be a single- or mixed-pressure apparatus; it is furthermore possible to equip the waste-heat steam generator with additional firing. According to the current state of the art, such a combination unit is capable of achieving efficiencies of well over 50%. It is evident that the trend is to attempt to further develop these fossil-fired power plants, firstly as regards better utilization of fossil reserves and secondly on the assumption that, on this basis, any advance in technology has a disproportionately beneficial effect. In gas turbine groups, a not insignificant proportion of the turbine output has to be used for driving the compressor, with the result that an increase in the pressure drop in the gas turbine, which should lead to a higher yield in terms of the efficiency of the plant and could be achieved via a higher compression of the working air in the compressor, is therefore of little or no overall benefit since this extra output from the gas turbine would be lost in the form of higher consumption of the shaft power by the compressor.